Partial relinquishment report on EL 7239, 24-05-1991 to 23-05-1994

Abstract

Ashton Mining did not undertake any diamond exploration work within the relinquished portion of EL 7239. This report summarises all work undertaken on the relinquished portion of EL 7239 since grant. A review of the 1983 aeromagnetic survey data revealed a major basement structure similar to that associated with the McArthur Basin Pb-Zn-Ag deposit. The available photography and Thematic Mapper scene over the licence area were studird, and a comprehensive review of previous work was completed, together with a field inspection. Detailed airborne magnetic data was obtained and the NW trending structure (Wallhallow Bore Fault) was further defined. Airborne magnetic data suggests this structure is extensive and post-Proterozoic movement has occured. Unfortunately, cambrian basalt cover masks the magnetic character of the Proterozoic basement. Water bore data was obtained and added to the database of Open File drilling information. Very few of these holes reached basement stratigraphy, because the cover sequences are in excess of 100m thick. One RC drill hole totalling 109m was drilled in the relinquished area, terminating in Bukalara Sandstone. Drilling was unsuccessful as the Proterozoic basement was not reached. Depth of cover in the relinquished portion was likely to be prohibitive for systematic exploration. It was recommended that the 84 blocks be relinquished.